Performance evaluation of secondary loop low-temperature heat pump system for frost prevention in electric vehicles

Heating performance attenuation and frosting in the air conditioning system make electric vehicles unusable in harsh winter weather. A solution to the secondary loop low-temperature heat pump air conditioning system is proposed in this paper. The frost-prevention performance of the secondary loop heat pump air conditioning system under various low-temperature conditions was studied in a typical electric vehicle. The traditional direct heat pump air conditioning system scheme was also tested for the sake of comparison. The secondary loop heat pump air-conditioning system performs better in terms of heat transfer and system COP than the traditional heat pump in low temperatures. The secondary loop heat pump system functions stably and efficiently within 5 h under severe frosting conditions. To this effect, the proposed technology is a workable solution for electric vehicle air conditioning systems in -20 to 0 degrees C environments.